Establish the existence of the heavy H-baryon dibaryon through coupled-channel dynamics

Establish whether the heavy H_b dibaryon associated with the =00 channel exists by performing a full coupled-channel calculation that includes the relevant singly bottomed baryon-baryon channels.

Background

The paper studies singly bottomed dibaryons using a single-channel resonating group method and a chiral quark model. For the =00 channel, which has the same quark content as the proposed heavy H_b dibaryon, the calculation finds no bound state, whereas the and channels are bound.

Earlier work had suggested that an H_b state might lie below the threshold, but its existence was not conclusively established. The authors therefore identify a full coupled-channel calculation in =00 as necessary to determine whether channel coupling can generate or clarify such a state, and state that this calculation will be pursued in future work.

References

However, since their method provided only a lower limit for the mass and neglected the Pauli repulsion between quarks belonging to different diquarks, the existence of a bound $H_b$ state could not be established conclusively. In our calculation, the $\Lambda\Lambda_b$ channel with $IJ=00$, which has the same quark content as the $H_b$ dibaryon, does not support a bound state. In contrast, the $\Sigma\Sigma_b$ and $\Sigma{}\Sigma_b{}$ channels are found to be bound, with binding energies of -43.13 and -33.68 MeV, respectively. Therefore, the present single-channel results alone do not support a bound $H_b$ state. A full coupled-channel calculation in $IJ=00$ is therefore necessary to clarify this possibility and will be pursued in our future work.

— Systematic study of baryon-baryon interactions in singly bottomed systems  (2609.04616 - Du et al., 4 Sep 2026) in Section 3, subsection “Bound state calculation” (discussion following Tables 1 and 2)